Abstract
Neuronal processes are being studied in behaving animals, as opposed to surgically or pharmacologically altered preparations, with increasing frequency. Among the more recent advances in this direction is the successful intracellular recording of cortical neurons in unanesthetized, uncurarized, and mechanically restrained animals 18,19. Chase et al. 4, (see also ref. 16) have succeeded in recording from inside trigeminal motoneurons during natural sleep. We now report a surgical technique and neuronal identification strategy for the intracellular recording of lumbosacral motoneurons in naturally sleeping and waking cats. Nine cats weighing 2.2-3.5 kg were implanted in a standard manner for sleep recordings and head restraint under pentobarbital anesthesia 17. Electrodes were placed for recording the electrocorticogram (ECoG), electrooculogram (EOG), electromyogram (EMG), and ponto-geniculo-occipital (PGO) waves from the lateral geniculate bodies (LGB). Two 63 #m wires (Stableohm 675, California Fine Wire Co., Grover City, CA) with bared tips were attached to the tibial nerve and run subcutaneously to a cranial connector as described by Bromberg and Fetz z. For eventual recording in the lumbosacral cord, the skin above vertebrae L4, L5, and L6 was incised, the spinal processes removed, and the underlying muscles parted. The laminae were completely exposed, while the body and pedicle were exposed in the middle longitudinal third of each segment. Stainless steel screws (1/4, 4-40) were inserted in the body of the vertebrae as shown in Fig. I. Knurled nuts (6-32) were placed on L4 and L6 and a 12 mm ID plastic cylinder and cap was placed on L5. The entire assembly was fused together with acrylic cement, and the surrounding skin was bonded to the sides of the acrylic mound with cyanoacrylate ester adhesive. Antibiotics and nutritional supplements were regularly administered throughout the survival period. Within two days after surgery the cats walked normally except for lower back rigidity. The experimental apparatus consisted of a simultaneous cranial 17 and lumbar immobilization. The lumbar region was fixed by clamping the two lumbar
Published Version
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